Many users interact with various Internet-based services using mobile devices such as personal digital assistants (“PDAs”) and cell phones. Common Internet-based services include map services, navigation services, and search services. A map service, which may be provided as a web service, provides maps of various locations as requested by users. For example, a user driving a vehicle may request using a cell phone that the map service provide a map of the surrounding area. The map service may determine the user's current location based on global positioning system (“GPS”) coordinates provided by the cell phone and download a map of the surrounding area to the cell phone so that it can be displayed to the user. The map service may provide maps based on locations other than the user's current location. For example, a user may use a map service when planning a vacation in a distant city. In such a case, the map service provides a map of the distant city. The map service may be accessible by any computing device (e.g., a desktop computer) and not just mobile devices.
A navigation service provides directions for travel between locations. For example, a user driving a vehicle may use a PDA to specify a destination location and request that the navigation service provide directions from their current location to the destination location. The navigation service, after determining the user's current location (e.g., using GPS information), prepares the directions and downloads the directions to the user's PDA for presentation to the user. The directions may be in various formats. For example, the directions may be presented by highlighting a map or by providing a written or an audible list of turn instructions.
A search service may allow users to search for enterprises (e.g., retail outlets, governmental entities, and schools) that satisfy a search request or query. For example, a user driving a vehicle may use a PDA to request a search service to identify the restaurants that are nearby. The user may enter the query “nearby restaurants.” The search service would identify restaurants that are near the user's current location and provide to the user's PDA a listing of those restaurants or a map indicating the locations of the restaurants.
Many Internet-based services, such as map services, navigation services, and search services, rely on advertising revenue as their sole source of revenue or to augment other sources of revenue. When a service receives a request, the service may provide advertisements along with the response to the request. A navigation service may provide advertisements that are in some way related to the destination location. For example, if the destination location is Washington, D.C., then the navigation service may provide advertisements for tour companies, restaurants, airlines, and so on that service Washington, D.C. A map service may similarly provide advertisements that are in some way related to the area of the map being displayed, and a search service may provide advertisements related to the search terms and the user's current location.
A difficulty, however, with providing advertisements that are in some way related to a location is that the advertisements are often ranked based on distance from the advertised service to the user's current location. For example, if a user in Seattle enters “nearby restaurants,” a search service may identify advertisements for coffee outlets, fast-food outlets, and full-service restaurants that are within a five-mile radius of the user's current location. The search service may rank eight coffee outlets first because they are nearest to the user (e.g., within one mile of the user) and rank a coffee outlet that is two miles away higher than a restaurant that is three miles away. The user, however, is unlikely to be interested in a coffee outlet that is two miles away, but is likely to be interested in a restaurant that is three miles away. In such a case, the ranking based on distance would not necessarily reflect a correct ranking from the user's perspective. In addition, when a user is reviewing a map, a map service may provide advertisements for enterprises whose locations are not on the map. For example, a map service may provide an advertisement for a restaurant that is off the map. In such a case, the user may not have a good idea of how far away the restaurant is or how difficult it would be to get to the restaurant.